Research On Video Streaming Transmission Mechanism In NDN

With the rapid development and extensive application of the Internet,the network traffic grows rapidly,which makes the traditional TCP/IP network expose more and more problems in mobility,security,scalability,quality of service and so on.The researchers have proposed a number of content-centric future Internet architecture to copy with the problems of IP network,in which Named Data Network(NDN)is the most promising future network architecture.With the transformation of users' requirements and the emergence of new services,content is the development trend of the Internet,and the video has become the mainstream of the network services,so that it has important research value to transmit video data efficiently and reliably in NDN.NDN adopts a Pull-based transmission model.The user sends the interest packet to obtain the unique data packet and there is a “one to one” relationship between the interest packet and the data packet.However,this request mode is not suitable for the delay sensitive services.Each node has the function to cache data in NDN,and the design of the cache strategy needs to consider specific services.The strategy does not combine with the characteristics of the video data,which will not be able to highlight the advantages of caching.Considering of that problem,the third chapter of this thesis proposes a cache strategy that considers double level popularity based on the Pull-Push hybrid request mode(Pull-Push-DLP).This thesis proposes the Pull-Push hybrid request mode according to the continuity of requested video data.The request mode sends part interest packet to obtain the complete video file and it reduces the quantity of the interest packets.Under the hybrid request mode,the thesis designs cache strategy based on the popularity.The thesis considers the effect of the popularity of the video file and the potential value of the video chunks on cache strategy,and combines the relevance of the internal data chunks of the video file,video file size and other files inherent characteristics.The nodes provide differentiated services for different popularity files and the valuable contents to users will be stored in different node of the return path.The simulation results show that the cache mechanism based on the Pull-Push hybrid request mode can obtain more video data packets in the same time and reduce the delay of user requests,and improve the network cache performance.It realizes the efficient transmission of video data.NDN adopts the retransmission mechanism to recover the lost data.However,it may have serious delay between packet loss and retransmisson,and the unrestricted retransmission mechanism may aggravate network congestion,which cannot meet the delay sensitive video service.In view of the above problems,the fourth chapter of this thesis proposes the packet loss recovery mechanism for video data in NDN.This mechanism combines the adaptive forwarding of interest packets and the cache characteristics of nodes to realize packet loss recovery of video data.The adaptive forwarding algorithm is designed for the packet loss recovery.By detecting the link status,the optimal forwarding interface is obtained to avoid the interest packet forwarding the congestion link,thus alleviating the link congestion and providing the link condition for the packet loss recovery.The cache policy is designed for the packet loss recovery.When the forwarding interface of the data occur congestion,the data will be stored in the node to provide data source conditions for the packet loss recovery and the forwarding interface will record name information of dropped data.The policy real-time detects interface queue buffer space and obtains the dropped data packet in the content store of the node by name information.The interface re-forwards the data packet to achieve the recovery of lost video data rapidly.When the intermediate node cannot recover the lost packet,the delay control of the retransmission mechanism will be applied to recover the loss of data packets.The simulation results show that the video data packet loss recovery mechanism proposed in this thesis can realize the fast recovery of lost data under the condition of satisfying the real-time performance of video data,and improve the service quality of video data and realize the reliable transmission of video data.